Major Sixth

In classical music from Western culture, a sixth is a musical interval encompassing six staff positions (see Interval number for more details), and the major sixth is one of two commonly occurring sixths. It is qualified as major because it is the larger of the two. The major sixth spans nine semitones, its smaller counterpart being the minor sixth, spanning eight semitones. For example, the interval from C to A is a major sixth, as the note A lies nine semitones above C, and there are six staff positions from C to A. Diminished and augmented sixths span the same number of staff positions, but consist of a different number of semitones (seven and ten).

A commonly cited example of a melody featuring the major sixth as its opening is "My Bonnie Lies Over the Ocean".

The major sixth is one of consonances of common practice music, along with the unison, octave, perfect fifth, major and minor thirds, minor sixth and (sometimes) the perfect fourth. In the common practice period, sixths were considered interesting and dynamic consonances along with their inverses the thirds, but in medieval times they were considered dissonances unusable in a stable final sonority; however in that period they were tuned very sharp, to the Pythagorean major sixth of 27/16. In just intonation, the major sixth is classed as a consonance of the 5-limit. A major sixth is also used in transposing music to E-flat instruments, like the alto clarinet, alto saxophone, E-flat tuba, trumpet and horn (instrument) when in E-flat as a written C sounds like E-flat on those instruments.

The major sixth occurs in first inversion minor chords, second inversion major chords, and either version of a diminished chord. It occurs in the second and third inversions of a dominant seventh chord. The septimal major sixth is approximated in 53 tone equal temperament by an interval of 41 steps or 928 cents.